1. Field of the Invention
The present invention relates generally to wheels for human powered vehicles such as bicycles, wheel chairs and the like, and especially to a novel wheel with a unique rim and unique spoke nipples.
2. Description of the Prior Art
Spokes and rims for wheels for human powered vehicles have been the subject of numerous innovations over the years.
U.S. Pat. No. 2,937,905 (Altenburger) discloses a tubeless tire rim and a way to connect spokes to it.
U.S. Pat. No. 5,769,584 (Claes), the disclosure of which is incorporated herein by reference, discloses a nut for a spoke in a bicycle wheel. The nut has an enlarged head with a rounded collar, which permits the nut to align itself in a spoke hole of the rim when a spoke connected in the nut is put into tension by the nut. The nut or nipple is what is commonly referred to as an external nipple, which means that a portion of the nipple extends through the spoke hole in the rim and is accessible outside of the rim cavity. That external portion of the nipple has four flats that cooperate, in a known manner, with a nut spanner for rotating the nut externally, i.e., outside, of the rim.
The structure disclosed in Claes includes a lining or eyelet 13, which is seated in each spoke bore in the rim of the wheel. Each lining or eyelet has an upper flange that rests on an upper surface of the rim bottom, a cylindrical side wall, which extends downwardly from the upper flange and through the spoke opening in the rim and a lower flange which rests on a lower surface of the rim. The patent appears to be silent about how such an insert or eyelet is secured to the rim, but clearly it involves an upset operation to seat the eyelet in the rim within the spoke opening. The insert defines a ring on which the rounded collar is supported. Due to the external portion of the spoke nut extending through the spoke hole or opening in the rim, and through the spoke hole or opening in the eyelet or insert, and the clearance required for the spoke and the external portion of the nut to pivot to the degree required to accommodate what is defined hereinafter as the centering angle and the torsional angle, the spoke hole or opening is, necessarily, many times larger than the diameter of the spoke itself. As a consequence, the surface on which the rounded collar rests is relatively small because of the large opening required to accommodate the spoke and the external portion of the nipple.
European Published patent application no. EP 0 714 791 discloses an external nipple with a rounded collar which rests on an insert called a guide. Swiss Patent No. 355041 discloses an external nipple with a rounded collar that rests on an insert in the rim. French Patent No. 1,498,599 discloses an external nipple with a conical collar that rests on an insert in the rim. French Patent No. 1,516,857 discloses a rim insert for supporting an external spoke nipple. German Patentschrift No. 583 902 discloses a rim insert for supporting an external spoke nipple. European Published patent application no. EP 0 860 301 discloses an external nipple with a rounded collar and a rounded insert for supporting the nipple on the rim.
Bicycle wheel makers have long struggled with the problems that arise due to the fact that the spokes in a bicycle wheel do not extend radially from the hub to the rim. In other words, the spokes are skewed relative to a true radius. This is illustrated in FIGS. 1 and 2 hereof, which are based upon FIGS. 2 and 1, respectively, of U.S. Pat. No. 4,583,787 (“Michelotti”), the disclosure of which is incorporated herein by reference.
FIG. 1 illustrates what I call the centering angle of a spoke, in the context of a rim 10 that has a radius R. In the drawing, the radius R coincides with the center plane of a wheel including the rim 10, the center plane being perpendicular to the axis of rotation of the wheel and intersecting the center line of the rim. The longitudinal axis, designated SA, of a spoke (not shown) attached to a left hub flange (not shown) deviates from the rim radius R by an angle designated CA for centering angle. In the drawing, the spoke axis SA intersects the rim radius R outside of the rim 10. Because of this deviation, a spoke connected to the rim 10 and a left hub flange (not shown) exerts a lateral force which is balanced, more or less, depending on the spoking pattern, by an opposite lateral force exerted by one or more spokes (not shown) connecting the rim 10 to a right hub flange (not shown). These lateral forces keep the rim centered in the wheel center plane and provide essential lateral stability to radially spoked wheels and to tangentially spoked wheels. Thus, the name centering angle.
FIG. 2 illustrates what I call the torsional angle of a spoke, in the context of a rim 10 that has a radius R. In the drawing, the radius R coincides with the center plane of a wheel including the rim 10, the center plane being perpendicular to the axis of rotation of the wheel and intersecting the center line of the rim 12. The longitudinal axis, designated SA, of a spoke 14 attached to a right or left hub flange (not shown) deviates from the rim radius R by an angle designated TA for torsional angle. Because of this deviation, which is found in tangentially spoked wheels, primarily used as rear driving wheels, the spoke 14 is operable to transmit a pulling or torsional force from a rotating hub to the rim 12, tending to cause the rim to rotate. Thus, the name torsional angle. Generally speaking, there is no torsional angle in wheels that are radially spoked. Generally speaking, a spoke that has a torsional angle also has a centering angle.
Michelotti discloses eyelets or inserts which are intended to support the spoke nut or nipple in a skewed position, corresponding as required to the centering angle or the centering and torsional angle, as necessary. This approach does not and cannot account for dynamic displacements and distortions of a spoke under dynamic conditions. Further, the use of eyelets or inserts, as noted above, is labor intensive. In the case of Michelotti's eyelets, however, exact positioning and orientation of the eyelets is required to support each spoke, as intended.